System and method for communicating over an 802.15.4 network

ABSTRACT

A method of reducing data transfer while increasing image information over an 802.15.4 network includes obtaining an image with a sensor, modulating a representation of the image using a first 802.15.4 modem, sending the representation of the image to a coordinator, demodulating the representation of the image using a second 802.15.4 modem, and digitally enhancing at least one of the representation of the image and the image. A system for communication over an 802.15.4 network includes a sensor for obtaining data, the size of the data being at least an order of magnitude greater than the size of an 802.15.4 packet, a first 802.15.4 modem coupled to the sensor, a buffer for temporarily storing the data to allow transmission of portions of the data; the buffer being coupled to the sensor, a coordinator coupled to the sensor, the coordinator being capable of communicating with a computer, and a second 802.15.4 modem coupled to the coordinator.

PRIORITY AND RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/538,279, filed Aug. 12, 2019, which is a continuation of U.S. patentapplication Ser. No. 16/272,606, filed Feb. 11, 2019, now U.S. Pat. No.10,382,122 issued Aug. 13, 2019, which is a continuation of U.S. patentapplication Ser. No. 16/115,269, filed Aug. 28, 2018, now U.S. Pat. No.10,205,515 issued Feb. 12, 2019, which is a continuation of U.S. patentapplication Ser. No. 15/926,766, filed Mar. 20, 2018, now U.S. Pat. No.10,069,561 issued Sep. 4, 2018, which is a continuation of U.S. patentapplication Ser. No. 15/709,853, filed Sep. 20, 2017, now U.S. Pat. No.9,948,382 issued Apr. 17, 2018, which is a continuation of U.S. patentapplication Ser. No. 15/256,115, filed Sep. 2, 2016, now U.S. Pat. No.9,806,796 issued Oct. 31, 2017, which is a continuation of U.S. patentapplication Ser. No. 14/521,629, filed Oct. 23, 2014, now U.S. Pat. No.9,461,735 issued Oct. 4, 2016, which is a continuation of U.S. patentapplication Ser. No. 13/621,572, filed Sep. 17, 2012, now U.S. Pat. No.8,976,767 issued Mar. 10, 2015, which is a continuation of U.S. patentapplication Ser. No. 12/611,443, filed Nov. 3, 2009, now U.S. Pat. No.8,358,639 issued Jan. 22, 2013, which is a continuation of U.S. patentapplication Ser. No. 11/235,429, filed Sep. 26, 2005, now U.S. Pat. No.7,636,340 issued Dec. 22, 2009, which claims priority to U.S.Provisional Patent Application Ser. No. 60/612,901, which was filed Sep.24, 2004, each of which is hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

This application relates generally to data communication andparticularly to data communication using the wireless IEEE 802.15.4protocol over a WPAN (wireless personal area network) optimized for lowpower, low data rate networks.

BACKGROUND INFORMATION

The use of imaging technology is exploding with the advent of low-costmega pixel digital cameras and cameras inside cell phones. Cities areroutinely rolling out cameras in high-risk areas to help deter crime orprovide background on events. Webcams, or cameras attached to a personalcomputer, continue to grow in popularity and free services are expandingto support their use, such as Yahoo! Messenger. Wireless home monitoringand control products are hitting the market with wireless 802.11 cameraswhich require tethering to a power source but can send their images andvideo to a personal computer located somewhere nearby. Society isbecoming more aware of digital imaging technologies and theiradvantages.

CMOS (Complementary Metal Oxide Semiconductor) is the technologypopularly used to make computer processors such as the Pentium. As asubstitute for CCD (charge coupled device) chips, CMOS imagers allow acamera with lower power consumption, lower signal-to-noise ratio, andsmaller overall design. CMOS imagers have been on the market since thelate 1990's, but have seen a spike in popularity as they have beenadopted into cell phones since about 2002. With the huge volumes ofcellular phones, the price and performance of CMOS images have beenrapidly improving, and they are challenging CCD's for image quality.

A brief history of the IEEE 802.15.4 protocol development begins asfollows: whereas IEEE 802.11 (WiFi) was concerned with features such asethernet matching speed, long range (100 m), complexity to handleseamless roaming, message forwarding, and data throughput of 2-11 Mbps;WPANs (Wireless Personal Area Networks) are focused on a space around aperson or object that typically extends up to 10 m in all directions.The focus of WPANs is low-cost, low power, short range, and very smallsize. The IEEE 802.15 working group currently defined three classes ofWPANs that are differentiated by data rate, battery drain, and qualityof service (QoS). The present invention concerns the last class. Thefirst class, a high data rate WPAN (IEEE 802.15.3) is suitable formulti-media applications that require very high QoS. Medium rate WPANs(IEEE 802.15.1/Bluetooth) will handle a variety of tasks ranging fromcell phones to PDA communications and have QoS suitable for voicecommunications. The last class, a low rate WPANs (IEEE 802.15.4/LR-WPAN)is intended to serve a set of industrial, residential, and medicalapplications. These applications have very low power consumption, a costrequirement not considered by the above WPANs, and relaxed needs fordata rate and QoS. The low data rate enables the LR-WPAN to consume verylittle power.

The IEEE 802.15.4 wireless protocol is still in its infancy and is beingrolled out primarily in applications such as sensors, interactive toys,smart badges, remote controls, remote metering, and home and industrialautomation. The 802.15.4 protocol supports data rates of 250 kbps at2.405-2.480 Ghz with 16 channels (world-wide), 40 kbps at 902-928 Mhzwith 10 channels (Americas), and 20 kbps at 868.3 Mhz with 1 channel(Europe). The protocol supports automatic network establishment by thecoordinator; a fully hand-shaked protocol for transfer reliability; andpower management to ensure low power consumption. The wireless IEEE802.15.4-2003 standard was approved in May of 2003 and was published inOctober of the same year. The standard is still under furtherdevelopment with 2 additional task groups, 802.15.4a and 802.15.4bcontinuing the development. Current areas of development (as ofSeptember 2005) include resolving ambiguities, reducing unnecessarycomplexity, increasing flexibility in security key usage, andconsiderations for newly available frequency allocations among others.

General requirements of sensor/control networks include that they can bequite large, employing 255 clusters of 254 nodes each (64,770 nodes);are suitable for latency-tolerant applications; can operate veryreliably for years without any operator intervention; have very longbattery life (up to several years from an AA cell); very lowinfrastructure cost (low device and setup costs); very low complexityand small size; and device data rates and QoS (Quality of Service, i.e.,delay, jitter, throughput, and reliability) needs are low.

The IEEE 802.15.4 standard was developed to address the low power,low-bandwidth market; primarily focused on controls signals. In generalterms, 802.15.4 is seen as one of the lowest-bandwidth wirelesstechnologies available on the market today, and provides thecorresponding benefit of long battery life. Presentations typically showthe following:

TABLE 1 Technology Range Data Rate 802.15.4 WPAN to WLAN <0.25 Mbps802.15.1 (Bluetooth) WPAN >0.1 Mbps; <1 Mbps 802.11 (WiFi) WLAN >1 Mbps;<100 Mbps

Zigbee is a protocol layer that sits “on top” of 802.15.4, and seeks toestablish an interoperability standard for many companies to adopt, andto enable a smarter network with intelligence. Zigbee, or 802.15.4, sitsbelow Bluetooth in terms of data rate. The operational range of ZigBeeis typically stated as 10-75 m compared to 10 m for Bluetooth. Zigbeeuses a basic master-slave configuration suited to static star networksof many infrequently use devices that talk via small data packets.Bluetooth's protocol is more complex since it is geared towards handlingvoice, images, and file transfers in ad-hoc networks. Bluetooth devicescan support scatternets of multiple smaller non-synchronized networks(piconets). It only allows up to 8 slave nodes in a basic master-slavepiconet set-up. Zigbee nodes spend much of their time sleeping, but theprotocol is optimized for quick wake up and response. When a Zigbee nodeis powered down, it can wake up and get a packet in around 15 msecwhereas a Bluetooth device would take around 3 sec to wake up andrespond.

Another way of looking at the various technologies and where 802.15.4fits:

TABLE 2 Wi-Fi Bluetooth Zigbee Name GPRS/GSM 802.11b 802.15.1 802.15.4Application Wide Area Web, Cable Monitoring Focus Voice & E-mail,Replacement and Control Data Video System 16 MB+ 1 MB+ 250 KB+ 4 KB-32KB Resources Battery Life 1-7  0.5-5 1-7  100-1000+ (days) Network Size  1   32  7 255/65,000 Bandwidth 64-128+ 11,000+ 720 20-250  (KB/s)Transmission 1,000+   1-100 1-10+  1-100+ Range (meters) Success Reach,Speed, Cost, Reliability, Metrics Quality Flexibility Convenience Power,Cost

The wireless cameras available today use the high data rate 802.11bwireless technology and due to their high power consumption, typicallyrequire 110 or 220-volt “wall” power. These solutions suffer fromseveral drawbacks. Some of these units are battery powered but requiremany batteries, such as 6 AA cells, and only work for a short timeperiod, such as 2 to 4 hours, before exhausting the batteries. As aresult of the many battery cells, these units are large and heavy. As aresult of the power cords, placement and view are very limited, or powercords must be run making installation and movement inflexible. Current802.11b wireless imaging transfer solutions require complex setup andconfiguration, as they are typically “IP Addressable” and connect to theinternet via an 802.11b wireless ethernet connection. They must bemanaged and configured as if they are other computers on the internet.While current 802.11b wireless imaging transfer solutions may allow from1 to N cameras within a local area network, these are not automaticallyconfigured for 1 to 254 nodes as with the 802.15.4 protocol. The 802.11bsolutions are relatively expensive and run from $200 to $300 per camera.Finally, current 80211b wireless imaging transfer solutions do not allowthe passing of messages from node to node, so are limited by theirdirect range from end node to hub.

Digital images typically require anywhere from 10 Kilo Bytes up to 2,000Kilo Bytes of storage. VGA images are 640×480 pixels, or 307,200 pixels.Each Pixel typically has 2 bytes of data associated with it. Therefore,a regular VGA image will contain 614,000 Bytes of data. JPEG compressionroutines can compress this image 10:1; 20:1; 30:1; and more, down tounder 20K Bytes. At a 30:1 compression, a 20K Byte image can betransported at 15K Bytes/Second in 1.25 seconds. Additional JPEGcompression and information reduction routines can bring this image downto, say, 9K. However, each reduction in size will correspond to areduction in the information content of the picture, and a reduction inthe clarity of the resulting picture. Lesser quality picture standards,such as QCIF (176×144) or QQVGA (160×120) are available to reduce theinitial image size, however, these will display on correspondinglysmaller screens or views such as a cell phone screen. A VGA imagedisplays as roughly a 6″×8″ image on a standard computer screen.

Processing techniques can “shrink” the image size at the expense ofimage quality. For a given image size, say 30 Kilo Bytes, a highbandwidth system can transfer images quickly; while a low bandwidthsystem requires more time. The IEEE 802.15.4 wireless protocol operatesat several speeds: 240, 40, and 20 kilo bits per second. At 240 kilobits per second, a 30 kilo byte image would take 1 second to transfer,and with overhead would take up to 100% longer, or 2 seconds. At 40 kilobits per second, a 30 kilo byte image would take 6 seconds to transfer,and with overhead would take up to 100% longer, or 12 seconds. This isseen as very long latency. Since most image transfer applicationsrequire low latency (i.e., you hear a baby cry and want to immediatelysee the image) and since the IEEE 802.15.4 wireless protocol isconsidered low-bandwidth, in the past it has not been consideredsuitable for image transfer applications. Previously, any file sizegreater than an order of magnitude greater than the 802.15.4 packet sizehas not been feasible.

A Zigbee system includes several components. The most basic is thedevice. A device can be a full-function device (FFD) or areduced-function device (RFD). A network should include at least oneFFD, operating as the PAN coordinator.

A solution is needed that enables many, low-cost, low-maintenance,small, battery-powered cameras to be flexibly placed in a networkconfiguration. These cameras should be light enough to be placed withadhesive, thus allowing the user to “peel n stick” the cameras inout-of-the-way places. These cameras should cost less than $50 a piece,compared to the $200-$300 802.11b solutions available on the markettoday. They should be self-configuring and announce themselves to theWPAN coordinator (FFD) that they exist. The software that runs on thedesktop should capture the presence of each camera end node and showit's health with signal strength and battery life, so that setup andmaintenance of the 802.15.4 network is absolutely simple. Wirelessethernet should not be required to arrange a network, but rather, thedevices themselves should create their own network and the coordinatorcan be powered directly from the USB connection of a mobile lap-topcomputer, thus, a network can be established anywhere the camera RFD'scan communicate with their FFD coordinator. This enables extrememobility of the network. Finally, the cameras should provide for somekind of alert, either a beep or light flash, to indicate that they arecapturing images to address general public concerns about being“watched”.

Thus a need exists to bring together CMOS imaging technology, the IEEE802.15.4 wireless protocol, and control software to create a flexible,low-cost solution to information delivery using images.

SUMMARY OF THE INVENTION

One of the objects of the present invention is to overcome theaforementioned problems and deficiencies. For example, an aspect of thepresent invention builds on digital imaging technologies using two newerpieces of technology. It combines the wireless IEEE 802.15.4 low power,low bandwidth protocol with CMOS imaging devices. In order to combinethe imager solutions with an 8-bit HCO8 hardware architecture, theinventors propose storing one or more images in a temporary location, orbuffer, so that it may be moved from end node to hub via the 802.15.4architecture's transport limitations of 127 Bytes per packet. Thisbuffer may exist on the Protocol Handler processor or on an adjunctflash component on the end node. The Transchip 5740 will allow up to 60Kof storage on the Applications Processor; while other solutions willforce the image through to the Protocol Handler on the End Node, wherethere is 32K or more of Flash storage space for temporary buffering ofthe image. Once the image is “stored” in the Applications Processor orin the Protocol Handler (within a flash memory for example), the802.15.4 transport mechanism may move the picture in small “chunks”.This 802.15.4 transport architecture allows for 127 Bytes per packet.However, the effective payload is approximately 100 Bytes per packet, orper frame. Depending on the mode of operation of the 802.15.4 network(i.e., Beacon or Polling), the image stored in flash memory as, forexample, 30K Bytes, can be either streamed or moved in 100 Byte “chunks”depending on acknowledgments and error correction within the algorithms.This is dependent on the inherent protocol handling of the 802.15.4stack and logic of the network. Thus, an aspect of the present inventionpermits extraction of useful information (up to and including the entirefile, although that is rarely necessary) in a timely manner from filesizes greater than an order of magnitude (i.e., ten times) greater thanthe 802.15.4 packet size transferred over an 802.15.4 network.

Thus, an aspect of the present invention takes advantage of a suite oftechnologies to enable the delivery of images over low-power RF networksusing battery-powered cameras. Several advantages of these solutions aretheir integration into the 802.15.4 RF network, simplicity of setup andmaintenance, flexibility of placement, and battery powered cameras. Dueto their low current consumption and hibernation modes, the RF Networks'components can operate on battery power for long periods of time. Theinventors have integrated digital CMOS imaging and the new, low-powerIEEE 802.15.4 RF standard to create a “Plug and Play” remote wirelesscamera monitoring solution. Some “off the shelf” components may be used(such as the Transchip 5740 imager and the Freescale 802.15.4 ZigBeeTransceiver (Evaluation Kit DIG528-2, part number 80000528000 R0203.DSN,Rev R02.03); however, the integration represents a novel concept. Theintegrated 802.15.4 cameras operate using flexible battery power andwith the advantages of 802.15.4, should have long battery life. Theinventors have added software to enable the solution to “plug and play”with up to 254 cameras controlled from 1 Coordinator, or Hub, pluggedinto the USB port of a personal computer. The USB port provides thepower for the Coordinator. The 802.15.4 protocol enables us tocommunicate over ranges from a few meters to tens of meters, enabling acomplete surveillance solution to cover a home or office complex. Therange of the system can be extended substantially with the addition of arepeater.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a first exemplary embodiment of an802.15.4 network according to the present invention.

FIG. 2 is a block diagram showing the WPAN 802.15.4 FFD Coordinator/Hubof FIG. 1.

FIG. 3 is a block diagram showing the WPAN 802.15.4 RFD Camera End Nodeof FIG. 1.

FIG. 4 is a block diagram showing a second exemplary embodiment of an802.15.4 network according to the present invention.

FIGS. 5A-5D are a circuit diagram showing the interfacing between theTC5740 CMOS Imager of FIG. 4 and the Freescale HCS08 MicroController.

Throughout the figures, the same reference numerals and characters,unless otherwise stated, are used to denote like features, elements,components or portions of the illustrated embodiments. Moreover, whilethe present invention will now be described in detail with reference tothe figures, it is done so in connection with the illustrativeembodiments.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

FIG. 1 depicts an exemplary embodiment of an 802.15.4 network accordingto the present invention. The basic system operates via the interactionof several components as shown in FIG. 1. In the basic setup, a computer10 such as a personal computer (PC) with some control software requestsan image from the system. The request could be for an image from one ormultiple cameras within the network. The request may be based on aparticular time period that has passed, or may be based on a triggeringevent (such as a door opening and triggering a sensor). The request isfirst directed to the Coordinator or Hub 20, which is attached to thecomputer via, perhaps, a USB connection. The Coordinator is built usingan 802.15.4 Low Power RF Radio. The Hub 20 then communicates using alow-power RF protocol with the appropriate Repeaters 30 and Camera EndNodes 40 to acquire the image. The Repeaters may be fabricated using an802.15.4 Low Power RF Radio. End Node Cameras may come in many forms anddue to their small size, may be integrated into common household devicessuch as a smoke alarm 50. Additional integrated camera devices 50 whichare integrated with other sensors may be present. The Camera End Nodes40 may be integrated with an 802.15.4 Low Power RF radio. The Camera EndNodes 40, 50 are intelligent and accept commands from the computer's 10control software such as “Zoom”, “Pan”, “Low Quality Image”, or “HighQuality Image”. Finally, the network may contain other 802.15.4 sensorsfor intelligence such as a door proximity switch 60, or other networksensors. These may communicate with the Coordinator/hub to captureimages upon a pre-determined logic. For example, from FIG. 1, theopening of a door triggers a signal from the door proximity switch 60 tothe Coordinator 20, which requests an image from the camera focused onthe doorway 40.

Detailed System Operational Description for Integration of a CMOSImager/Camera into an IEEE 802.15.4 Network

FIG. 2 is a block diagram of the Coordinator/Hub 20. A request for animage may come from the internet to the PC or locally from the PCcontrol software. The request is then directed to the Coordinator/Hub 20and enters through the PC USB connection 203. The request is captured bythe Protocol Handler Processor 202, and waits for the next availabletimeslot from the 802.15.4 protocol stack and RF modem 201. Using thenetwork logic, the Protocol Handler Processor 202 requests an image fromthe camera end node 40. In an alternate embodiment, the Coordinator 20may be IP addressable, and thus a gateway PC 10 may not be required.

FIG. 3 represents the Camera End Node, block 40, from FIG. 1. At theCamera End Node 40, the system may “wake up” upon a pre-determinedtimeslot based on the 802.15.4 protocol to see if a request for an imageexists from the Coordinator/Hub 20. It may also “wake up” because of atriggering event (e.g., door opening, alarm, change of temperature,manual selection, etc.). Here, RF modem 405 is communicating with RFmodem 201. Within an 802.15.4 system, these timeslots may be from a fewhundred milliseconds out to many minutes between “wake-up” periods.

When an image request exists, this request is received by the Camera EndNode at RF Modem 405 and held within the Protocol Handler 407. Therequest is then sent through the glue board components 408 to the TC5740Camera Assembly 409. (FIGS. 5A-5D provides further detail on theinterfaces between 407 and 409.) The image command may contain a numberof camera adjustment requests such as focus, pan, zoom, low quality,thumbnail, high quality, etc. image adjustments. The camera will takethe picture, process it through its Imaging DSP, and hold the processedJPEG image within the camera assembly's internal RAM. Alternativeimplementations may allow the image to be stored within the local flash406. The camera 409 will then communicate back through the Glue BoardComponents, 408, with the Protocol Handler 407 and will beginpassing/streaming the image back to the Coodinator/Hub 20 using theconnections between the two 802.15.4 RF modems, 405 and 201, inapproximately 100 byte packets.

If requested, the camera may also take a very high quality image andstore the entire image within the picture buffer of the camera assembly409 or of the camera end node's flash 406. The camera may process theimage further into a thumbnail or lower quality/lower density image.This thumbnail or lower quality image may be transmitted back throughthe Glue Board Components, 408, with the Protocol Handler 407, etc. asdescribed above. The transmission of a highly compressed, low resolutionthumbnail normally provides adequate information that there is nothingof interest back to the requestor. If further information is requestedon this image, the camera may take a new image or simply take theexisting image in memory and process the image further with digitalzooming, panning, cropping, variable resolutions, and lossy compressiontechniques to provide maximum information using minimum bandwidth. Ifrequested, maximum detail could be provided via the entire pixel bit mapusing a lossless compression technique.

The camera end node 40 may include extendable flash memory 406 to enablethe camera to take from 1 to N images using pre-determined logic withinthe Protocol Handler Processor 407 and store these images (or streamingvideo) into local memory 406. The flash memory 406 may take the form ofa “removable” storage such as USB-sticks, Compact Flash (CF), SecureDigital (SD) Flash cards, or other removable media. These images wouldthen be retrieved at a later time using system logic or when theCoordinator/Hub 20 acquires, or comes in range of, the end node, orvice-versa (the end node moves within range of the Coordinator/Hub).

The camera end node 40 may include a user interface 410 forcommunicating the camera end node status. This interface might be assimple as an LED that would blink to communicate “on”, “taking animage”, “communicating with the network”, etc. Alternatively, the userinterface may include a multi-color LED, multiple LED's, a transducer,or a very basic LCD for communicating status, how many images have beentaken, or how many images are stored on resident flash. This userinterface 410 may also enable a “friendly” surveillance camera, whichcould provide an advance warning that it is about to take a picturethrough a beep or LED flash.

The Coordinator/Hub 20 generally acts as a “pass-through” and sends theimage to the PC 10 to be assembled. Flash memory 204, on theCoordinator/Hub 20 provides for increased flexibility to enable largeimages or many images to be captured and contained within theCoordinator via pre-determined logic in the advent that a host PC 10 isunavailable or unable to pull the image. In some cases, the Coordinatorwill be “IP addressable” and connect directly to the Internet to receiveimage requests for the 802.15.4 network.

When the image is completely sent and checksum verified, it may bedisplayed within a graphics window on the PC 10, or transmitted outthrough the internet to the requesting source.

In the above description, the 802.15.4 “stack” was performing theCoordinator/Hub to Camera End Node communications, with from 1 to N endnodes, along with clear channel scanning and collision avoidancealgorithms; and beacon or timeslot adjustments. These capabilities arebuilt into the 802.15.4 software stack and are easily controlled via theProtocol Handler Processors such as 407 in the End Node block diagram.

Camera End Node (40) Behavior at Startup

Referring to FIG. 3, the Transchip 5740 camera assembly that theinventors have tested requires that it receive its firmware foroperating the Imaging DSP and image sensor upon power-up. To accommodatethis, the inventors have inserted a 64 KB flash eeprom, 406 to hold thefirmware. Upon powerup, the firmware is downloaded from the EEProm intothe TC5740 sensor. Note this firmware may be from 35 KB to 60 KB and isdetermined by Transchip.

Behavior of a Repeater, Block (30):

The block diagram of a repeater 30 within FIG. 1 may be almost identicalto a Coordinator/Hub 20, with the exception that 203 from FIG. 2 shouldcontain voltage management components to enable the repeater to beplugged into a regular power outlet, such as a 110V or 220V wall-socket,or 5V USB connection to a PC. A repeater is preferably “always on”, andthus would drain power from a battery source quickly unless plugged intoa steady power source. Another Coordinator/Hub 20 plugged into adifferent PC may also act like a repeater if the network is configuredappropriately. In this case, its block diagram would be the same as 20.

Behavior of an Integrated Camera, Block (50), or Integrated Repeater,Block (70):

Referring to FIG. 4, the block diagram of an integrated Camera 50, willdepend on the sensor and associated logic programmed into its protocolhandler processor. A smoke detector is depicted in the system setupexample. In general, the integrated camera 50 block diagram will lookvery similar to the Camera End Node 40 block diagram (see FIG. 3), withthe addition of more sensors, similar to 409, connected back through aconnector block similar to 408 to the protocol handler processor 407.These “glue board components” could be combined into 408 or separatedonto separate boards for an improved platform design approach.

An integrated camera similar to 50 of FIG. 4 could act both as a reducedfunctional device where the camera co-exists with the smoke detector; asa reduced function device where the camera is integrated with the smokedetector to send images only upon alarm; as a repeater whereby it simplycontains the 802.15.4 RF modem to extend range of the camera end nodes40; or finally as both an integrated camera and repeater since it'spower supply would enable an “always on” operation, and the camera couldenable images upon request or upon smoke detector alarm.

There are numerous options for the behavior of an integrated camerasensor such as 70 from FIG. 4. For example:

TABLE 3 RF Camera Behavior (Y or N) Comments Repeater Yes Camerafunction could be either dependent (FFD) or independent of smoke sensor.To extend range of end nodes, to act as a clandestine range extender.End Node Yes Camera function could be either dependent (RFD) orindependent of smoke sensor. Repeater No To extend range of the endnodes, to act as (FFD) a clandestine range extender End Node No To alertthe intelligent network of an event, (RFD) such as smoke detectionBehavior of “Other Sensors”, Such as a Door Proximity Sensor (60) fromFIG. 4:

The block diagram of other sensors, such as Block “60” from FIG. 4, willdepend on the sensor and associated logic programmed into it's protocolhandler processor. A door proximity switch is depicted in the systemsetup example. In general, the integrated door proximity switch 60 blockdiagram will look very similar to the Camera End Node 40 block diagramfrom FIG. 3 with the addition of more sensors, similar to 409, connectedback through a connector block similar to 408 to the protocol handlerprocessor 407. These “glue board components” could be combined into 408or separated onto separate boards for an improved platform designapproach.

End Node Sensor Types Beyond Cameras, Door Proximity Switches, and SmokeAlarms, Blocks 408 and 409:

While the inventors have focused on a few particular sensors, such ascameras, door proximity switches, and smoke alarms, many other optionsexist for an integrated end node. In particular, an intelligent networkwould contain motion, light, smoke, water, temperature, and soundsensors among others. These sensors would integrate into the networkwith some “glue” components 408 and the actual sensors themselves 409from the Integrated Camera End Node 40 block diagram. Those skilled inthe art would be able to integrate any of these standard sensors intothe network topology.

FIGS. 5A-5D are a circuit diagram showing an exemplary embodiment of theinterfacing the inventors have tested. FIGS. 5A-5D depict theinterfacing between an exemplary Camera (the TC5740) and the FreescaleHCS08 MicroController. The 24-pin connector titled “Zigbee Radio” camefrom the Freescale 13192 design, while the 20-pin connector titled“camera module” came from the TC5740 camera module. Remaining circuitrywas placed on the interface board 408 to provide interconnection, EEProm406, oscillator and battery management between the camera and modem.

It is contemplated that many versions or embodiments of the inventionmay be provided. Although the invention has been described with acertain degree of particularity, it should be recognized that elementsthereof may be altered by persons skilled in the art without departingfrom the spirit and scope of the invention. As such, the foregoingdescription has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed. Obvious modifications orvariations are possible in light of the aforementioned teachings. Forexample, there are many applications for wireless, battery-powered,“peel n stick” cameras operating within an 802.15.4 network. Theinventors foresee low-cost home monitoring applications, businesssecurity/surveillance applications, “intelligence” applications wherecameras are used on conjunction with other devices to manageinformation, pet-cams and refrigerator-cams, and integrations into otherdevices such as lamps, TV's, and clocks, etc.

1. A system comprising: a battery-powered end node capable of beingattached to a moveable item; a modem in the end node, the modem beingcapable of communicating over an 802.15.4 network; a coordinator,capable of communicating over the 802.15.4 network and capable ofmonitoring signal strength from the end node; a computer, capable ofcommunicating with the coordinator; a camera comprising a CMOS imagesensor and a low power RF radio, the camera being capable of operatingon battery power and capable of communicating over the 802.15.4 network;a buffer in the camera configured to store portions of a picture;wherein, after the monitored signal strength at the coordinator is belowa threshold: the coordinator is configured to alert by at least one ofaudibly, visually, and transmitting a notification; at least one of thecoordinator and the computer is configured to transmit a command to thecamera to take the picture.
 2. The system of claim 1, the picturecomprising data of a size in bytes at least an order of magnitudegreater than the size in bytes of an 802.15.4 packet.
 3. The system ofclaim 1, wherein the threshold is based on RSSI measurements.
 4. Thesystem of claim 1, comprising a further coordinator, the furthercoordinator being capable of: communicating over the 802.15.4 network,monitoring signal strength from the end node, and communicating with thecomputer.
 5. The system of claim 1, wherein, based on predeterminedlogic, at least one of the coordinator and the computer is configured totransmit a further command to the camera to take a further picture.
 6. Amethod comprising: with a coordinator, monitoring, over an 802.15.4network, signal strength from a battery-powered end node attached to amoveable item; when the signal strength is below a threshold: with thecoordinator, alerting by at least one of audibly, visually, andtransmitting a notification; transmitting, by at least one of thecoordinator and a computer capable of communicating with thecoordinator, a command to take a picture with a camera; wherein, thecamera comprises a CMOS image sensor, a low power RF radio, and abuffer, the camera being capable of operating on battery power andcapable of communicating over the 802.15.4 network, and the buffer beingcapable of storing portions of the picture.
 7. The method of claim 1,wherein the picture comprises data of a size in bytes at least an orderof magnitude greater than the size in bytes of an 802.15.4 packet. 8.The method of claim 1, wherein the threshold is based on RSSImeasurements.
 9. The method of claim 1 comprising: with a furthercoordinator, monitoring, over the 802.15.4 network, signal strength fromthe battery-powered end node attached to the moveable item; when thesignal strength is below the threshold: with the further coordinator,alerting by at least one of audibly, and visually, and transmitting anotification; and transmitting, by at least one of the furthercoordinator and a computer, a command to take a picture with the camera.10. The method of claim 1, further comprising: based on predeterminedlogic, transmitting, by at least one of the coordinator and thecomputer, a further command to the camera to take a further picture 11.A non-transitory computer readable medium comprising a set of executableinstructions to direct a processor to perform the method of claim
 6. 12.A non-transitory computer readable medium comprising a set of executableinstructions to direct a processor to perform the method of claim
 7. 13.A non-transitory computer readable medium comprising a set of executableinstructions to direct a processor to perform the method of claim
 8. 14.A non-transitory computer readable medium comprising a set of executableinstructions to direct a processor to perform the method of claim
 9. 15.A non-transitory computer readable medium comprising a set of executableinstructions to direct a processor to perform the method of claim 10.